Electronic watt and watthour meters for measuring electrical energy supplied from a source of alternating current electric energy and which are susceptible to manufacture, at least in part, in solid state semiconductor, monolithic integrated circuit form, are well known and have been described in a number of prior art patents and publications. See, for example, the following U.S. patents issued in the name of Miran Milkovic, the inventor of the present application, and assigned to the General Electric Company:
U.S. Pat. No. 3,875,508, issued Apr. 1, 1975 "Metering Electrical Energy (KWH) In Single Phase Systems" PA0 U.S. Pat. No. 3,947,763, issued Mar. 30, 1976 "C-MOS Electronic KWH Meter And Method For Metering Electrical Energy" PA0 U.S. Pat. No. 3,955,138, issued May 4, 1976 "Electronic Energy Consumption Meter With Input Transformer Having Single Resistance Terminated Secondary Winding Coupled To C-MOS Switches Driven By Pulse Width Modulated Control Signals" PA0 U.S. Pat. No. 4,056,775, issued Nov. 1, 1977 "Electronic KWH Meter Having Internal Power Supply And Error Correction System" PA0 U.S. Pat. No. 4,217,546, issued Aug. 12, 1980 "Electronic Energy Consumption Meter And System With Automatic Error Correction" While the electronic measuring circuits described in each of the above-noted U.S. patents is satisfactory in many respects, there is always the need for improvement particularly with regard to the cost, size and complexity of components employed in the circuits.
One serious problem encountered with all measuring circuits of the above-described type including those listed above, is with respect to the sensors employed with the circuits and the necessary interface connections required to couple the sensors to the circuits. One of the elements employed with electronic measuring circuits of the above-noted type, is a conventional instrument current transformer having primary and secondary windings for developing an output signal voltage that is proportional to the current flowing in the primary winding, and supplying the same to the measuring circuit for processing. These conventional current transformers are relatively large and bulky, heavy and expensive and add substantially to the overall cost, size and weight of electronic measuring circuits employing such transformers for current sensing purposes.